小猿圈python学习-属性方法property

定义
属性方法的作用就是通过@property把一个方法变成一个静态属性

class Student(object):
stu_num = 0
def init(self,name):
self.name = name
@property
def fly(self):
print("%s is flying…" % self.name)
s = Student(“Mjj”)
s.fly()
调用会出以下错误， 说NoneType is not callable, 因为fly此时已经变成一个静态属性了， 不是方法了， 想调用已经不需要加()号了，直接s.fly就可以了

Mjj is flying…
Traceback (most recent call last):
File “/day6_面向对象进阶/属性方法.py”, line 14, in
s.fly()
TypeError: ‘NoneType’ object is not callable
正常调用
s.fly
输出
Mjj is flying…
property应用场景
好吧，把一个方法变成静态属性有什么卵用呢？既然想要静态变量，那直接定义成一个静态变量不就得了么？well, 以后你会需到很多场景是不能简单通过 定义 静态属性来实现的， 比如 ，你想知道一个航班当前的状态，是到达了、延迟了、取消了、还是已经飞走了， 想知道这种状态你必须经历以下几步:

1. 连接航空公司API查询

2. 对查询结果进行解析

3. 返回结果给你的用户

因此这个status属性的值是一系列动作后才得到的结果，所以你每次调用时，其实它都要经过一系列的动作才返回你结果，但这些动作过程不需要用户关心， 用户只需要调用这个属性就可以，明白 了么？

class Flight(object):
def init(self,name):
self.flight_name = name
def checking_status(self):
print("connecting airline company api… " )
print("checking flight %s status " % self.flight_name)
return 1
@property
def flight_status(self):
status = self.checking_status()
if status == 0 :
print(“flight got canceled…”)
elif status == 1 :
print(“flight is arrived…”)
elif status == 2:
print(“flight has departured already…”)
else:
print(“cannot confirm the flight status…,please check later”)
f = Flight(“CA980”)
f.flight_status
cool , 那现在我只能查询航班状态， 既然这个flight_status已经是个属性了， 那我能否给它赋值呢？试试吧

f = Flight(“CA980”)
f.flight_status
f.flight_status =3
输出， 说不能更改这个属性，我擦。。。。，怎么办怎么办。。。

Traceback (most recent call last):
connecting airline company api…
File “/day6_面向对象进阶/属性方法.py”, line 41, in
f.flight_status =3
AttributeError: can’t set attribute
checking flight CA980 status
flight is arrived…
当然可以改， 不过需要通过@proerty.setter装饰器再装饰一下，此时 你需要写一个新方法， 对这个flight_status进行更改。

class Flight(object):
def init(self,name):
self.flight_name = name
def checking_status(self):
print(“connecting airline company api… " )
print(“checking flight %s status " % self.flight_name)
return 1
@property
def flight_status(self):
status = self.checking_status()
if status == 0 :
print(“flight got canceled…”)
elif status == 1 :
print(“flight is arrived…”)
elif status == 2:
print(“flight has departured already…”)
else:
print(“cannot confirm the flight status…,please check later”)
@flight_status.setter # 修改
def flight_status(self,status):
status_dic = {
0 : “canceled”,
1 : “arrived”,
2 : “departured”
}
print(”\033[31;1mHas changed the flight status to \033[0m”,status_dic.get(status) )
f = Flight(“CA980”)
f.flight_status
f.flight_status = 1
输出

connecting airline company api……

checking flight CA980 status

flight is arrived…

Has changed the flight status to arrived

还可以删除

@flight_status.deleter  #删除
def flight_status(self):
    print("status got removed...")

f = Flight(“CA980”)

f.flight_status

f.flight_status = 1

del f.flight_status